package com.company;

import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class HJ10 {
    public static void main(String args[]){
        Scanner in = new Scanner(System.in);
        String line=in.nextLine();
        Set<Character> s=new HashSet<>();
        int count=0;
        for(int i=0;i<line.length();i++){
            if(!s.contains(line.charAt(i))){
                count++;
                s.add(line.charAt(i));
            }
        }
        System.out.println(count);
    }
}
